I recently got the Red Box (Essential 4e Starter Kit or whatever it's called) and have played through the adventure with some friends.

I have no idea what I need now – specifically, what books I need to get. My knowledge of D&D is entirely derived from the Red Box. I've heard talk of "Essentials books" and "Core books". (Apparently I can only make certain characters with certain books?) What are these and which do I need?

Basically, I'm looking for a list of books/sets I should get so that I can carry on playing.

I whole-heatedly recommend the D&D Insider option in my answer, in addition to all the books you get a lot of adventure modules for free from dragon and dungeon magazine.
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Joshua Aslan SmithOct 10 '13 at 13:24

@waxeagle As written this sounds like it might be a dup, but I think the core question here is more specific than the other, given the last line about specific books. I'm going to give it an edit to bring that to the fore.
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SevenSidedDieOct 10 '13 at 15:39

@SevenSidedDie tbh there's a bunch of good starting out with 4e questions on where to go and what books to buy. There are good dupes to that question too.
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wax eagleOct 10 '13 at 16:35

3 Answers
3

As per Joshua's answer, start with the three core books. With those, any basic campaign will open up to you.

To start a new campaign, you have a few options.

1: Build your own.

Building your own campaign can be quite rewarding, but also quite challenging. There are plenty of guides, both on this site and on the web abroad. Look for them and learn how to create an adventure of your own for 4.0.

2: Find/Buy a module

Campaign modules are basically new adventures that you can run. Some are available online (Look for 4.0 modules), and some can be bought.

3: Get an experienced DM

If you want an adventure but aren't sure where to start yourself, find someone who is experienced with 4.0 to run a campaign for you. DMs are looking for players all the time, and they'd be happy to lead you through a campaign, maybe even teach you the ins and outs of advanced DMing. Just make sure your group is okay with the DM you pick.

New books that expand the game and offer additional classes/rules/etc. can also help your game grow. But these three suggestions will get you started on a new campaign.

In essence, there are two kinds of books: those for the DM; and those for players.

As a new DM, it might be a good idea to run pre-made adventures until you are confident enough to tackle it on your own. To this end, I recommend choosing a low-level game because they are much easier to keep the game moving during combat.
Once you make the decision to run your own game, the DM guide 2 is a great book, and the other monster manuals can be nice-to-have's.

Players are usually much more keen to help with the costs of buying books if they see what they can get from them. Books with additional player options are a good idea. The players handbook 2 & 3 are really good choices. Let your players know about the Power books (Martial Power, Arcane Power, etc.) as this might encourage them to buy books themselves to give their own character more options.

D&D Insider is a monthly subscription that gives you access to all published 4e content (both books and web, insider exclusives through dragon and dungeon magazines). This content is accessed via online tools such as the Character Builder and Online Compendium as well as other, DM-centric tools such as the encounter builder and monster builder tools. The advantages of going the D&D Insider route is that its a far cheaper way to get access to all the materials, the tools are very helpful and updated with errata (note: Errata updates for the character builder usually lag a month behind published material). The only cons are you don't have physical books in your hand and can miss out on some of the fluff or DM guidelines and you are paying a sub (monthly, tri-monthly, or yearly).